Despite a brilliant amateur career, Clarke lasted until the 17th pick in the second round because he was diagnosed as a diabetic as a teenager.

Captained the Philadelphia Flyers to Stanley Cups in 1974 and 1975. The "Broad Street Bullies" were the first expansion team to win the Cup.

Won the Hart Memorial Trophy 1973, 1975 and 1976.

Played in the NHL All-Star Game in 1970, 1971, 1972, 1973, 1974, 1975, 1977 and 1978.

Captained Team Canada to victory in the 1976 Canada Cup.

The WHL named the award for its top scorer after Clarke.

His number 16 was retired by the Flyers in 1984.

Clarke retired after the 1983-84 NHL season, having scored 358 goals and 852 assists for 1210 points and 1453 penalty minutes in 1144 games. At the time of his retirement, he was 4th all-time in assists and 10th in points.

Wayne Gretzky has remarked that it was Clarke's play "from behind the net" that inspired him to improve that area of his game. Most regard Gretzky as the best ever from that position on the ice.